Faux holiday Prime Day 2017 was another huge win for Amazon as its biggest sales day ever, especially of its own devices, while it saw the biggest one-day gain in Prime membership, already at an estimated 85 million U.S. members.

Prime Day pulled in $1 billion in revenue, based on separate estimates from Cowen & Co. and JP Morgan Chase, according to Bloomberg, triple Amazon’s average daily volume in 2016.

Amazon said that sales on Prime Day were up 60% compared to the same 30-hour period in 2016; the event was extended by six hours this year. Its Echo Dot voice-activated device was the biggest seller and no wonder – it was promoted endlessly, featured on the company’s main page and sold at 50% off its normal price.

In terms of price matching, Walmart.com and its ancillary Jet.com came closest to Amazon on Prime Day, according to Market Track as reported by CNBC, but didn’t come close to matching all Amazon’s prices and had some items priced significantly higher.

Experts said Amazon’s main focus with Prime Day this year was its Alexa line of smart speakers – Echo, Amazon Tap and Echo Dot – in order to add more voice-activated, ecommerce-enabled hooks into the home.

“Last year it was great promotions of Fire TV devices, and this year it was Echo devices at half prices, as well as Alexa-enabled tablets,” said Josh Lowitz, partner and co-founder of Consumer Intelligence Research Partners (CIRP), which came up with the estimate of Prime membership. “In the lead-up to Prime Day there were lots of email promotions to get people with an Echo prepared to use it to shop. And the pricing suggested they’re even more committed to getting Echo into more houses.”

Amazon offered some early-bird deals ahead of Prime Day via Alexa devices as a further enticement.

Stefan Weitz, executive vice president of advanced technology for Radial, said the company’s major retail clients saw a 318% increase in sales on their Prime Day deals compared to the average Tuesday in June, while one client (GNC) saw a 5x boost. But Weitz said taking part in Prime Day – either directly or through coinciding promotions – can be a “dangerous game” for retailers if their execution is less than flawless.

“You’re not just competing against Amazon on price, and they’ve been known to take tiny margins to gain share,” Weitz…